Global Variations in the Mineral Content of Bottled Still and Sparkling Water and a Description of the Possible Impact on Nephrological and Urological Diseases

Hydration for Adult Patients with Nephrolithiasis: Specificities and Current Recommendations

Nephrolithiasis affects around 10% of the population and is frequently associated with impaired dietary factors. The first one is insufficient fluid intake inducing reduced urine volume, urine supersaturation, and subsequently urinary lithiasis. Kidneys regulate 24 h urine volume, which, under physiological conditions, approximately reflects daily fluid intake. The aim of this study is to synthesize and highlight the role of hydration in the treatment of nephrolithiasis. Increasing fluid intake has a preventive effect on the risk of developing a first kidney stone (primary prevention) and also decreases the risk of stone recurrence (secondary prevention). Current guidelines recommend increasing fluid intake to at least at 2.5 L/day to prevent stone formation, and even to 3.5-4 L in some severe forms of nephrolithiasis (primary or enteric hyperoxaluria or cystinuria). Fluid intake must also be balanced between day and night, to avoid urinary supersaturation during the night. Patients should be informed and supported in this difficult process of increasing urine dilution, with practical ways and daily routines to increase their fluid intake. The liquid of choice is water, which should be chosen depending on its composition (such as calcium, bicarbonate, or magnesium content). Finally, some additional advice has to be given to avoid certain beverages such as those containing fructose or phosphoric acid, which are susceptible to increase the risk of nephrolithiasis.

Mineral content variations between Australian tap and bottled water in the context of urolithiasis

Objectives

The objective of this study is to investigate the variations in mineral content of tap drinking water across major Australian cities, compared with bottled still and sparkling water, and discuss the possible implications on kidney stone disease (KSD).

Materials and Methods

The mineral composition of public tap water from 10 metropolitan and regional Australian cities was compared using the drinking water quality reports published from 2019 to 2021 by the respective water service utilities providers. Specifically, average levels of calcium, bicarbonate, magnesium, sodium, potassium, and sulphates were compared with published mineral content data from bottled still and sparkling drinking water in Australia.

Results

The median or mean (depending on report output) mineral composition was highly variable for calcium (range 1.3 to 20.33 mg/L), magnesium (range 1.1 to 11.2 mg/L), bicarbonate (range 12 to 79 mg/L), sodium (range 3 to 47.1 mg/L), potassium (range 0.4 to 3.23 mg/L) and (sulphates range <1 to 37.4 mg/L). Calcium, magnesium and bicarbonate levels in tap water were lower than in bottled sparkling water. Consumption of 3 L/day of the most calcium rich tap water would fulfil 4.7% of the RDI, compared with 8.7% with bottled sparkling water. Consumption of 3 L of the most magnesium rich tap water would fulfil 8% of the RDI, compared with 13.6% with bottled sparkling water.

Conclusion

The mineral content of tap drinking water varied substantially across major Australian city centres. Bottled sparkling water on average provided higher levels of calcium, bicarbonate and magnesium and may be preferred for prevention of calcium oxalate stones. These findings may assist counselling of patients with KSD depending on geographic location in the context of other modifiable risk factors and 24‐h urine analysis results.

Variation in Tap Water Mineral Content in the United Kingdom: Is It Relevant for Kidney Stone Disease?

Introduction: The dissolved mineral content of drinking water can modify a number of excreted urinary parameters, with potential implications for kidney stone disease (KSD). The aim of this study is to investigate the variation in the mineral content of tap drinking water in the United Kingdom and discuss its implications for KSD. Methods: The mineral composition of tap water from cities across the United Kingdom was ascertained from publicly available water quality reports issued by local water supply companies using civic centre postcodes during 2021. Water variables, reported as 12-monthly average values, included total water hardness and concentrations of calcium, magnesium, sodium and sulphate. An unpaired t-test was undertaken to assess for regional differences in water composition across the United Kingdom. Results: Water composition data were available for 66 out of 76 cities in the United Kingdom: 45 in England, 8 in Scotland, 7 in Wales and 6 in Northern Ireland. The median water hardness in the United Kingdom was 120.59 mg/L CaCO3 equivalent (range 16.02−331.50), while the median concentrations of calcium, magnesium, sodium and sulphate were 30.46 mg/L (range 5.35−128.0), 3.62 mg/L (range 0.59−31.80), 14.72 mg/L (range 2.98−57.80) and 25.36 mg/L (range 2.86−112.43), respectively. Tap water in England was markedly harder than in Scotland (192.90 mg/L vs. 32.87 mg/L as CaCO3 equivalent; p < 0.001), which overall had the softest tap water with the lowest mineral content in the United Kingdom. Within England, the North West had the softest tap water, while the South East had the hardest water (70.00 mg/L vs. 285.75 mg/L as CaCO3 equivalent). Conclusions: Tap water mineral content varies significantly across the United Kingdom. Depending on where one lives, drinking 2−3 L of tap water can contribute over one-third of recommended daily calcium and magnesium requirements, with possible implications for KSD incidence and recurrence.

Could the region you live in prevent or precipitate kidney stone formation due to mineral intake through tap water? An analysis of nine distribution regions in Flanders

OBJECTIVES

To analyse the mineral content of tap water in Flanders and assess if the region one lives in could prevent or precipitate stone formation due to a difference in mineral content.

METHODS

Data from six water companies providing tap water to nine regions in Flanders regarding calcium, magnesium, potassium, sodium and sulphate content in tap water was retrieved. Minimum and maximum values were collected and compared between the different geographical regions.

RESULTS

The highest calcium level was found in region 9 with a value of 157.0 mg/L, which is almost 10 times the value found in region 8 (16.1 mg/L). Region 6 had the highest magnesium (31.8 mg/L), potassium (30.5 mg/L), sodium (126.6 mg/L) and sulphate (218.5 mg/L) levels. The lowest level of magnesium (2.7 mg/L) was found in region 1, which was almost 12 times lower as in Region 6. Region 9 had the lowest level of potassium (1.5 mg/L), which is a factor 20 lower than Region 6. The lowest sodium and sulphate levels were found in region 8 (6.8 mg/L and 3.0 mg/L), respectively. The difference between the highest and lowest level of sulphate was a factor 70.

CONCLUSION

There is a broad range in the minerals found in tap water between the different production sites in the nine distribution regions in Flanders. However, due to the high standards tap water has to meet in Flanders, the region one lives in will not lead to a higher or lower risk of kidney stone formation if the advised 2 to 3 L per day are consumed.

Special Issue 'Minimally Invasive Urological Procedures and Related Technological Developments'

The landscape of minimally invasive urological intervention is changing [...].